Detachable blade bit



10, 1 J. A. ROLAND 3,003,570

- DETACHABLE BLADE BIT Filed Sept. 24, 1958 2 Sheets-Sheet 1 J' OE A. LAND I ENTOR.

BY A PM Oct. 10, 1961 J. A. RQLAND DETACHABLE BLADE BIT v 2 Sheets-Sheet 2 Filed Sept. 24. 1958 30E A- ROLAND States 3,003,570 DETACHABLE BLADE BIT Joe A. Roland, 5117 Rocky Ridge Road, Dallas 32, Tex. Filed Sept. 24, 1958, Ser. No. 763,039 3 Claims. (Cl. 175-391) The present invention relates to improvements in detachable blade bits.

Various types of detachable blade bits, sometimes termed drag bits, have been proposed by the prior art. All of such constructions are formed by a plurality of cutting blades which are adapted to be held together by a bowl or some other similar ,type of adapter fitting thereabout to aid in initially positioning the blades rela tive to each other and for the purpose of retaining them in positionduring use of the bit.

Such adapters increase the diiiiculty of assembling the detachable blade bits for use and are generally undesirable, in that they encourage slipping of the blades relative to each other and relative to the drill string to which the bit is attached as the drill string is rotated to effect rotation of the bit.

The bowl or adapter also increases the initial cost of the bit, and since it is subject to wear during use of the bit, its repair or replacement increases the cost of drilling operations.

Another problem with drag bits or detachable blade bits of the prior art is that it has been somewhat difiicult because of the structural arrangement of the various components of the bit, to provide a bit with a seal which prevents or inhibits the leakage of fluid therefrom so that the fluid may be directed through the bit in a desired and predetermined manner for discharge thereof at the bottom of the hole being drilled. Improper fluid leakage causes wear of the bowl and thus increases the tendency or possibility for slippage to occur between the bit blades and the adapter or bowl.

Since detachable blade bits are not formed of one piece, but are formed of a plurality of parts which are held together, it can be readily appreciated that the tendency for the bit to separate in the hole into its components is encouraged by the very fact that it is not formed of a unitary construction. Normally, a great deal of vibration accompanies the drilling process, and this coupled with the rotary forces and other forces to which the bit is subjected as the drilling operation continues, applies a great strain to any drilling bit, and since a drag bit or detachable blade bit is formed of a plurality of parts, these strains are more likely to separate the bit during a drilling operation.

The present invention is directed to a construction for overcoming the above problems which are encountered in present drag bit constructions.

An object of the present invention is to provide a detachable blade bit construction which eliminates the adapter or bowl heretofore used with drag bit constructions.

Still another object of the present invention is to provide a drag or detachable blade bit construction formed of a plurality of blades which are adapted to be locked into position with a threaded segmented ring, whereby the ring and blades may be connected to a sub on the lower end of a drill string.

Yet a further object of the present invention is to provide a detachable blade bit construction which may be readily assembled and disassembled with a minimum of effort.

Still a further object of the present invention is to provide a detachable blade bit construction wherein a seal is formed between the bit and the drilling sub to which 2 the bit is connected to inhibit leakage of fluid between the bit and the sub.

Yet'a further object of the present invention is to provide a detachable blade bit construction, including a plurality of blades in a segmented threaded member which is adapted to lock on the blades, the threaded portion of the segmented ring forming a means for connecting the drill bit to a drilling sub, said threaded ring and shank being constructed and arranged to inhibit loosening thereof as the device is in operation in a well.

' Another object and advantage of the present invention is to provide a bit construction wherein the bit blades are precision machined to the necessary dimension for receiving the carbide inserts so that the carbide inserts are nested directly against the machined and forged bit blade without the necessity of providing backing of brass or bronze for the inserts.

Other objects and advantages of the present invention will become more readily apparent from a consideration of the following description and drawings wherein:

FIG. 1 is a side elevation illustrating the detachable blade bit construction of the present invention assembled and partially threaded into a drilling sub;

FIG. 2 is a perspective view of one of the blades of the bit of the present invention;

FIG. 3 is an exploded view showing the segmented ring and the assembled relationship of the bit blades 'ready'to receive the segmented ring thereon;

FIG. 4 is a sectional view on the line 4-4- of FIG. 1 showing the drilling bit in assembled relationship and partially threaded into a sub, which sub is in turn adapted to be connected to a drilling string so that rotation may be imparted to the drilling bit;

FIG. 5 is a sectional view on the line 5-5 of FIG. 1 showing the abutting relationship of the bit blades when assembled; and

FIG. 6 is a view somewhat similar to FIG. 3, but assembled and rotated slightly to show the opening in the lower end of the bit for discharge of drilling fluid therefrom.

In FIG. 3 of the drawings the drilling bit is generally indicated by the numeral 4 and is shown as including a plurality of blades designated by the numeral 5 which are fitted together and provided with shank 8 about which the ring 6 which is formed of the segmented half ring portions 6 and 7 are adapted to fit whereby the drilling bit may be threaded into the drilling sub indicated by the numeral 8' in FIG. 1. Any number of blades may be used as desired to form the drill bit, but as a practical matter it has been found that the number of blades used will generally not exceed three or four. Of course, under some circumstances it may be desirable to use more.

The shank 8 on one end of each of the blades 5 has the tapering, curved surface 9 thereon, which surface forms the arc of a circle as more clearly illustratedvin FIG. 4 so that when the blades are arranged together, the surface 9 on the shanks 8 form a complete circle which tapers from the inner end of the shank to the outer end thereof. When three blades are used to form the drilling bit, the surface 9 will form an arc of so that the three blades together will total 360 in angular measurement. Similarly, when a greater or lesser number of blades is used, the angular measurement or circumferential dimension of the shank will be changed correspondingly so that the blades when fitted together will form a total arcuate lengthof 360. 7

. The shank 8 terminates at the shoulder 11 which shoulder extends circumferentially about each of the shanks as illustrated in FIG. 1 of the drawings. The lower portion 12 of each of the blades 5 is thickened as indicated at FIG. 2 of the drawings to provide additional strength to the bit. The portion 13 of the blade 5 protrudes radially relative to the shank 8 and extends longitudinally of the blade as shown in FIG. 2 of the drawings. The lower end 14 of the radial extension 13 forms the cutting edges of the blade 5 and it will be noted that the portion 14 is formed into a plurality of stepwise cutting edges 15, 16 and 17. The radial extension 13 is flat as indicated at 18 in FIGS. 3 and 6 of the drawings, and provides a support for receiving the surface 19 of an adjacent blade.

It will be noted from FIG. 2 of the drawings that the surface 19 is formed on the edge of the blade 5 opposite the radial extension 13 a distance equal to the angular length of shank 8. The flat surface 18 of the radial extension 13 is recessed as illustrated at 20 along the lower edge 14 for receiving hardened material such as carbide or the like to increase the cutting life of each of the blades of the bit.

The back surface 22 of the lower portion 12 below the shoulder 11 is reinforced by means of the built up ridges 23, 24 and 25 to provide additional strength to the bit and to inhibit breaking or chipping thereof as the cutting edge engages with the formation during use of the bit in drilling operations. Each of the blades is provided with a longitudinally extending arcuate recess 23' therethrough so that when the blades are all positioned together, an opening as indicated by the numeral 24-" is provided through the bit for conducting drilling fluids therethrough during drilling operations.

Suitable means as indicated generally at 26 are provided for engaging the shanks 8 of each of the blades with the segmented locking ring 6' to inhibit relative rotation between the bit shanks and the segmented locking ring. As illustrated in the drawings, the means 26 is in the form of projecting pins 28 on each of the shanks 8 and openings 23 through the half portions 6 and 7 of the segmented ring 6'. When the two half portions 6 and 7 are fitted on the shanks 8, the projections 28 extend through the openings 29 to inhibit relative rotation between the segmented ring 6' and the blades 5.

Particular attention is directed to the construction as shown in FIGS. 3 and 4 of the drawings, wherein the interior surface 30 of each of the half portions 6 and 7 of the segmented locking ring 6' are tapered complementary to the tapered surface 9 on the shanks 8 so that the threaded half portions 6 and 7 fit snugly thereabout when positioned thereon. Additionally, a slot or groove 31 is provided in each of the threaded half portions 6 and 7 to accommodate slight movement thereof as will be described.

In assembling the drilling bit of the present invention, the blades 5 will be positioned together so that the surface 19 of one edge of one blade abuts the radial extension 13 of the adjacent bit blade 5 as shown in FIG. 5 of the invention. Thereafter the threaded segmented ring 6' is positioned upon the shank 8 of the assembled bits and the projection 28 fits in the openings 29 in each of the portions 6 and 7 of the segmented ring 6'. This prevents relative rotation between the blades and between the threaded segmented ring 6. The device is now ready to be screwed into a drilling sub indicated generally at 8', which drilling sub is connected on the lower end of a drilling string. The inside of the drilling sub is, of course, provided with threads and the drill bit is threadedly engaged into the drilling sub until the lower end 33 of the sub abuts the shoulder 11 on the drilling bit blades to form a metal to metal seal therebetween to inhibit leakage of fluid from the drilling bit as the device is in operation.

In some situations, it may be that there will be a slight variation in the fit of the segmented threaded ring 6 relative to the threads on the interior of the drill sub 8' and if this is the case, the grooves 31 extending longitudinaliy of each of the half portions 6 and 7 are adapted to provide for a certain amount of give or yield in the threaded segmented ring to aid in assembly of the device.

Additionally, the longitudinally extending grooves, as well as the complementary tapering surfaces 30 on the half portions 6 and 7 and the tapered surface 9 on the shank 8 effect a tighter fit between the drilling bit and the sub during drilling operations. While the drilling sub is being rotated to the right it should seem obvious that a certain amount of resistance will be offered thereto by the friction of rotation of the blades of the drilling bit and this resistance causes the drilling bit to be forced into tighter engagement on the drilling sub and a tighter seal is formed between the lower end 33 of the sub and the shoulder 11 on the blades of the drilling bit.

If it should become necessary to disassemble the device in the field, such disassembly may be accomplished merely by unthreading the drill bit from the lower end of the sub 8'. Since no collar or adapter is provided, it is unnecessary to worry about providing the proper size adapter or collar in replacing or in reassembling the device.

The seal between the end of the sub and the shoulder 11 prevents leakage of fluid from the bit so that the drilling mud may be discharged properly through the opening 24" in the bottom of the bit.

A curved longitudinally extending recess 24 is provided in each blade 5 so that when the blades are fitted together a fluid passage is formed through the assembled bit. This is best illustrated in FIGS. 2, 4 and 5 of the drawings. As fluid is circulated down through the drilling string, it will pass through the opening in the bit formed by the recess 24 in each blade and thereafter be discharged through opening 24" at the lower end of the bit. The seal formed by the end 33 of sub 8 and shoulder 11 prevents leakage of mud fluid from the bit and causes the drilling fluid to be discharged properly through the lower end of the bit as previously stated.

The recesses 29 along the lower edge 14 of the bit blade are precision machined to receive the hardened inserts shown at 20'. Heretofore the bit blades have been constructed with a relatively large recess 20 and then brass or bronze placed thereon to fill up the recess to the proper dimension to form the backing for the inserts 20'. This is undesirable because of the initial cost and because the inserts tend to work loose with such construction. When the recess 20 is formed to fit the inserts 20', then the brass backing can be eliminated.

Broadly the invention relates to a drag bit which eliminates the use of a collar or bowl and which provides a positive fluid seal to inhibit leakage of fluid from the bit.

What is claimed is:

1. A detachable blade rotary drilling bit adapted to be positioned on a drilling sub comprising, a plurality of blades each having a shank with a tapering surface thereon, said shanks each being of a circumferential extent to define substantially a complete circle when said blades are positioned adjacent each other to form a bit, a circumferentially extending shoulder on each blade defining the termination of said shank portion of said bit, a flat surface extending from each of said blades, said surface extending longitudinally of each of said blades and being in a radial plane of the circle formed by said blades when assembled adjacent each other, said surface defining a support for receiving and supporting an adjacent blade thereagainst when the blades are assembled adjacent each other, a segmented ring with each segment having an inner surface conforming complementary to said surface on said blade shanks whereby said segmented ring may seat about said shanks, cooperating means engaging between each of said shanks and each of said ring segments to lock said segmented ring and shanks together against relative rotation and against relative longitudinal movement, and a threaded surface on the exterior of said ring whereby said ring and shanks held therein may be engaged with a drilling sub, said cooperating engaging means including a projection on each of said shanks and an opening in each of said segments for receiving each of said projections of hardened, wear resistant material positioned in said therein. recesses to form cutting edges on each blade.

The comb,mat1n melted, m clalm 1 111c 1udmg References Cited in the file of this patent arcuate recess 1n each of sa1d blades extending 1ong1- UNITED STATES PATENTS tudinally of each of said shanks to form a circular open- 5 1 428 122 Smith Se t 5 1922 ing by said blades when positioned together for conduct- 490180 y 'g 1924 mg drilling through said blades. Shields J 7 3. The combination recited in claim 1 wherein the lower 53 Fraser 1929 end of each of said blades is formed by stepwise edges, 10 2 5 153 white Oct 20 1953 there being recesses in said stepwise edges, and inserts 2,666,622 Hawthorne Jan. 19, 1954 

